Whites and colors separated. If I have enough loads of laundry, I may even subdivide the loads into cold and warm otherwise I wash most things in cold water. Every so often I’ll also do a load of greasy shop towels and work clothes in hot water.
I do a lot of exercising and have clothing made of technical materials like Kool Max which shouldn’t be machine dried and/or no fabric softeners. I do these in a separate load in cold water and hang dry them.
My scrubs tend to get washed in their own load, not because I do much gross bodily fluid related work in them (I don’t) but because I have enough to last me a week, and then they need to be washed. Since they’re all the same weight and same general color family (I like to think of them as Modern Preschool) they make a nice load.
White socks and underwear make a load, with lots of bleach and hot water.
Towels make a load, because they need hot water but no bleach, and only fabric softener every once in a while (otherwise, they don’t towel due to wax buildup).
Bedsheets make a load, because a set of queen bedsheets is about the size of my washer, and if I do them together, they can go back on the bed before bedtime and I don’t have to fold sheets.
The rest of the clothes get separated by weight of the fabric, and then if the pile is especially huge, by “light” or “dark” colors. Weight of the fabric is most important to me, because I don’t want my tissue t-shirts to overcook in the dryer while the jeans are still damp. That’s hard on the fibers.
Reds (except for the scrubs, which have proven themselves colorfast) get their own laundry bag to pile up in, which means they don’t get washed all that often. Doing the reds is like opening Christmas gifts; I discover sweaters and shirts I totally forgot I had, and they feel new again.
I wash everything together, one big load, in our basement. Never had a problem, but then again I’m not picky. My gf does many seperate loads. She sometimes talks about doing her wash my way, but lacks the balls to try.
I pay a neighbor $5 per load to do mine. Works great. Drop the laundry off on my way yo work, pick it up at the end of the day. I have no clue what her strategy is but it’s all nicely folded and clean, which works for me.
My house is really small, and the bathroom is in the rear of the house next to the mud room. There’s hook ups for the washer and dryer in the mud room but I’m using the space for other stuff. I hate doing laundry anyhow.
Oops, forgot to add: I have a coin operated washer and dryer in my basement, three levels down. $1 for wash, $1 for dry. There are two other apartments in the building, we all share the one washer and dryer. So neither laundromat or quite my own.